The invention relates to an airbag module, and more particularly to a front-seat passenger air bag module with a cover cap.
U.S. Pat. No. 5,482,313 discloses a cover cap for a front-seat passenger airbag module. This cap is provided as a separate part in an orifice of the instrument panel below which the housing of the airbag module is located. Hooks are provided in the upper region of the housing. The hooks engage into orifices of elastic tongues of the cover cap. Furthermore, on the cover cap there are claws that engage under the instrument panel in the region of the orifice, so that the cover cap is detained. This type of fastening allows a lateral movement of the cover cap to a slight extent. In the event of a crash, the cover cap is torn open, without the instrument panel being damaged.
Japanese preliminary publication 7-117609 discloses a front-seat passenger airbag module which, on the housing, has latching means engaging into cutouts on side walls of a cover cap. Movement of the cover cap relative to the housing is thereby possible within defined limits.
These abovementioned types of fastening of a cover cap separate from the instrument panel make it easier to match up the bearing surface between the instrument panel and the cover cap of the front-seat passenger airbag module when the front-seat passenger airbag module is being mounted. On the other hand, there is the disadvantage that, even after the airbag module has been mounted, the cover cap can move slightly due to the gap existing between the cover cap and the instrument panel, which may cause rattling noises.
Furthermore, EP 0 739 788 discloses a cover for an airbag module in which two latching means are provided. The first latching means provided are elastic projections on side walls of the cover, said projections engage under the instrument panel. The cover rests with its edge, without lateral play, in a depression of the instrument panel and is retained there. The side walls of the cover have perforations, into which hooks of the airbag housing engage as second latching means. The perforations are substantially larger than the hooks, so that, after the airbag housing has been mounted, the cover cap is displaceable relative to the housing both in the vertical direction and in the lateral direction. However, because the cover cap has to fit exactly into the intended depression of the instrument panel, the cover cap must be manufactured with insignificant tolerances.
An object of the invention is to provide a cover cap and a housing of an airbag module that the cover cap is sufficiently moveable for mounting the airbag module, but does not have be manufactured with narrow tolerances.
In an airbag module, in particular a front-seat passenger airbag module, with a module housing and a cover cap having at least one side wall, the cover cap being a separate component which rests on a surrounding component, according to the invention two latching means are arranged. A first latching means allows a movement of the cover cap relative to the surrounding component and a second latching means allows a movement of the cover cap relative to the module housing.
In this arrangement, the cover cap can be latched together with the surrounding component, for example with the instrument panel, even before the housing of the airbag module is fastened to the motor vehicle. Nevertheless, lateral and vertical movements of the housing, which are necessary, for example, because of manufacturing tolerances, can be carried out. After the housing has been fastened, the cover cap can still be moved in the vertical direction, so that the cover cap could be latched even after the fastening of the housing.
In a first embodiment, the cover cap and the first latching means are provided such that the cover cap is moveable laterally and in the direction of travel before the housing of the airbag module is fastened to the motor vehicle, and the second latching means and the module housing are provided such that movement between a side wall of the cover cap and the airbag module housing is possible only vertically in relation to the cover cap.
In a second embodiment, the cover cap, for its vertical moveability relative to the surrounding component, has flexible tongues resting on the surrounding component and flexible first latching means, and the second latching means and the module housing are provided such that movement between the side wall of the cover cap and the module housing is possible in the lateral direction and in the direction of travel.
The number of degrees of freedom of each latching means is at most two. This means that, after latching, the first latching means either still allow a defined lateral movement of the cover cap, but no vertical movement of the cover cap, or allow a vertical movement, but no lateral movement. On the other hand, the second latching means may allow only a vertical movement or a lateral movement.
It is expedient to provide as a first latching means elastically deformable catch hooks that engage under the surrounding component of the motor vehicle. The second latching means provided may be bolts on the housing of the airbag module that engage into long holes in the side wall of the cover cap.
The catch hooks are preferably arranged peripherally on the cover cap. The size of the free space between the catch hooks and the cover cap is such that the cover cap is guided, free of play, on the surrounding component of the motor vehicle. In this case, because of the elasticity of the catch hooks, the freedom from play does not necessitate a high degree of accuracy in the manufacture of the cover cap.
It is expedient that, when the cover cap is arranged on the instrument panel of a motor vehicle, the catch hooks on the sides of the cover cap which run transversely to the direction of travel are more rigid than the catch hooks on the sides of the cover cap which run in the direction of travel. This counteracts a displacement of the cover cap in the direction of travel after the airbag module has been mounted, such displacement still being possible due to the arrangement according to the invention. In addition, displacement can be counteracted by the catch hooks having roughened contact faces and/or having bosses or ribs.
In the case of a cover cap differing from the rectangular shape, the orifice provided in the surrounding subassembly for the emergence of the airbag expediently has opposite edges which are parallel to one another and the distance between which is different in places and opposite which the catch hooks are located at the corresponding distance in places.